Apology Letters for Mistakes at Work

Dear {Recipient},

Thank you for contacting us regarding {issue}. We're very sorry that the {item/service} you received did not meet your expectations. We understand your disappointment and apologize for any inconvenience this has caused.

At {company name}, our customers' happiness is our number one priority. Thus, we {have gone ahead and shipped out a replacement/would like to offer you a X-month free subscription/something else} in order to make it up to you.

Again, thank you for bringing this issue to our attention. We are always looking for ways to improve our service, and your feedback is crucial to that process. Please don't hesitate to reach out to us again should you have additional concerns. Thank you.

Best regards,

{Your Name}

Dear {Recipient},

Please accept my sincere apologies for creating a false impression about {product/service} when we spoke {on the phone/via email} {last week/the other day/etc.}. I understand how the lack of information about {the price/features/etc.} could be misleading, which I assure you was not my intention.

To help you understand our {product/service} better, kindly refer to the {factsheet/link/etc.} I've attached.
Please don't hesitate to reach out to me should you have any further questions.

Warm regards,

{Your Name}

Dear {Recipient},

I'm sorry I failed to {file the records/enter the data/schedule the appointment/etc.} that you requested earlier. I didn't mean to be negligent, but {reason} prevented me from completing the task.

I'm not trying to come up with an excuse, though. Please let me know what I can do to sort this out. I'm willing to {stay back after office hours/reach out to the client/etc.}.

Sincerely,
{Your Name}

Dear {Recipient},

I apologize for failing to show up to my scheduled interview on {day of the week}. I know this reflects poorly on me as a job candidate, but I assure you I wouldn't have missed such an important appointment unless there was a very good reason.

Unfortunately, {reason for missing interview}, thus I had no choice but to miss my interview. I hope you'll consider rescheduling me. I'm really interested in the position as {reason for interest}.

Thank you for your kind understanding.

Sincerely,
{Your Name}